54 



KNOWLEDGE 



[Jax. 2(J, 1883 



of that atmosphere, that wore it suddenly stripped ofT, the 

 sun would shine not only with greatly increased bright- 

 ness, but with a bluish violet colour. In a very short 

 tiiue indeed that colour would seem white again to our 

 eyes, grown accustomed to the change ; after which, 

 the sudden restoration of the absorbing atmosphere 

 would change the sun to an orange-red orb, which 

 only after awhile would seem to our eyes a white globe 

 as before. But while the general absorptive action of 

 the sun is wonderful, the story is still more wonderful 

 which the spectroscope has to tell about the specific al'sorp- 

 tive effects due to its constitution. Wo find that, whereas 

 in our air the vapour of water is present (to condense into 

 water drops and form clouds at certain levels, and to 

 change to ice-crystals and form cirrus at higher levels), in 

 the sun the atmosphere is laden with the ■\-apours of iron, 

 copper, zinc, sodium, magnesium, and like elements, to form 

 clouds of metallic drops, great gatherings of metallic crystals, 

 while the rains that pour down towards the concealed true 

 globe of the sun are mighty showers of molten metal. When 

 a hurricane occurs in the sun, the clouds which form the sun's 

 surface are swept along, or whirled around, not at the rate 

 at which we measure our storms, but with a velocity 

 compared with which their swiftest motion is as rest. The 

 solar tornadoes rage, not over a few hundred square miles, 

 but over regions as large as the whole surface of the earth, 

 over hundreds, even thousands of millions of square miles; 

 and they travel over these enormous regions at a rate not 

 of so many miles per hour or per minute, but of many 

 miles, sometimes more than a hundred miles, in every 

 second of time. Such storms are in progress now, where 

 we see the spots upon the sun. Such storms tell us of the 

 activity of that great central engine whose throbs are the 

 life-beats of the solar system. 



W^e measure the sun's work, perforce, by our own 

 forms of work. We speak of his emission of light and 

 heat as corresponding to what would result from the 

 burning of eleven thousand millions of millions of tons 

 of the finest coal in every second of time. But what mind 

 can conceive the real vitality of that mighty orb which 

 seems so silent and so still in our skies ? The throbbing of 

 the great engine which beats out light and life to the 

 whole family of planets can only be seen by the mind's 

 eye, and as yet that eye is no more capable of seeing the 

 sun's work as it really is than is the bodily eye of seeing 

 the distant millions of suns which the great gauging tele- 

 scopes of the Herschels bring within our ken. Nor can 

 the mental ear hearken to the uproar and tumult with 

 which the work of the great central engine is accomplished, 

 or imagine what would be heard if one could visit that 

 spot which looks like a tiny speck on the sun's surface, and, 

 passing below the limits of the solar air so that sound 

 waves could reach him, could find (as assuredly he would, 

 if he could live at a temperature which turns the hardest 

 metal into vapour) all forms of noise known to us — the 

 roar of the typhoon, the crash of thunder, even the 

 hideous groaning of the eartli-throe — surpassed a million- 

 fold by what takes place within every square mile of that 

 disturbed region. 



One cannot wonder if many students of science are 

 eager to find out the real meaning of the sun spots, to 

 learn how they are generated, and to solve tho secret of 

 that strange law which brings them in undulations ten or 

 twelve years long over the surface of the sun. Still less 

 can one wonder if many should be attracted by theories 

 associating terrestrial phenomena, not in general (as they 

 must assuredly be associated) but in detail, with the pe- 

 riodicity of solar disturbance. It has been shown that the 

 earth as a whole responds to the solar action displayed in 



sun spots. There can scarcely be any doubt that the connec- 

 tion long since indicated by Sabine between the phenomena 

 of terrestrial magnetism and the condition of the sun's 

 surface with respect to spots is a real one. Not magnetic 

 relatious simply, but others which have only been asso- 

 ciated within recent times with magnetism, as the occur- 

 rence of auroral displays, itc, have been clearly associated 

 with the general condition of the sun's surface on the one 

 hand, and with the outbreak of specific sun spots on the 

 other. True, the great solar storms recognised, when 

 mighty masses of glowing gas have been flung fortli in 

 the form of prominences, have occurred without any 

 simultaneous auroral or magnetic disturbances on the 

 earth. But these are side issues, literally. The 

 solar energy is there directed not towards the 

 earth, but at a right angle or thereabouts with her 

 direction ; and we can hardly wonder if she does 

 not respond to these solar asides. Whenever the face of 

 the sun turned towards her has shown evidence of perturba- 

 tion she has responded quickly enough. The disturbance 

 of September, 1859, was answered by movements of the 

 magnetic needle at Kew, which, if not actually simulta- 

 neous, were so nearly so that the light of the sun itself 

 reached us no quicker than the influence exciting that mag- 

 netic disturbance. Nor did the tremulous response of the 

 perturbed earth last but for a moment. Throughout the 

 night that followed Arctic and Antarctic auroral banners 

 waved over the northern and southern hemispheres, being 

 visible in latitudes seldom reached by such displays. For 

 more than twenty-four hours, also, telegraphic communica- 

 tion was interrupted. 



Again, it seems clear that the temperature of the earth, 

 as a whole, is affected by the absence or presence of many 

 spots on the sun's surface. This has been shown, ap- 

 parently in an unmistakable way, by the underground ther- 

 mometers at Edinburgh and at Greenwich. But the rain 

 and wind cycles, the famine and financial crisis periods, 

 the recurrence of disasters and shipwrecks, bad vine 

 years, and so forth, in harmony with the sun spot waves 

 — these have not yet been established. It sounds con- 

 vincing when one cyclist notes that over a certain region 

 the north-east winds are wetter and the south-west 

 winds drier in sun-spotted times than when the sun is 

 free from spots. Others find it still more convincing 

 when some one else tinds that in another region the 

 reverse holds. And when it is further found that in 

 some regions no such effects at all can be discerned, 

 many find nothing disheartening in that. Still, it 

 must be remembered that antecedently this sort of 

 evidence was certain to be obtained whatever period had 

 been dealt with ; looking over a short range of time, one 

 would be sure to find some places where the weather 

 seemed to agree in one way with the period (any period 

 whatever), other places where the weather seemed to agree 

 in just the opposite way, and yet others where there seemeJ 

 to be no agreement at all. And when we learn that as our 

 survey ranges over time as well as over space, there appear 

 similar diversities, the places which had seemed to agree 

 one way or another no longer agreeing, it seems a little too 

 much to ask men to believe that there is a real connection, 

 but that while one place is affected one way, another is 

 affected in the opposite way, and that as time passes, the 

 effects vary. With such scope for difference and variation, 

 a pack of cards, shuffled at random, might be shown to 

 agree with weather cycles (red cards for fine weather, black 

 ones for bad, or vice versd ad libitum). Weather predic- 

 tions guided by sun spots would be no better, in that case, 

 than predictions based on coin-tossing as suggested by Sir 

 Edmund Beckett. — Times. 



